This application is a competitive renewal of the University of Pennsylvania Training Grant for Infectious Disease Fellows that was first funded in 2001. We are requesting funds to train two postdoctoral fellows a year in virology, bacteriology, parasitology or immunology, which is the same number of fellows supported in the current grant. The 19 mentors on this grant come from 6 departments at Penn, including the Departments of Medicine, Neurology and Microbiology in the School of Medicine, the Department of Microbiology in the School of Dental Medicine, the Department of Pathobiology in the School of Veterinary Medicine, and the Wistar Institute. The applicant pool comes mainly from the Adult Infectious Disease fellowship program at Penn and the Pediatric Infectious Disease fellowship program at the Children's Hospital of Philadelphia. Seven candidates were enrolled on this grant in the first funding cycle, including 3 MD/PhD fellows and one minority applicant. Four fellows are still in training, while three have graduated the program. One of the three graduates successfully competed for a K08 award while on this training grant. Candidates from the ID fellowship programs who enroll on this training grant do so after completing their first year of ID fellowship, which is entirely clinical. During that year applicants meet with members of the training grant executive committee, which is the governing body that decides who will be offered a slot on this grant. Once a candidate is selected, he or she meets with the PI (Dr. Friedman) and various trainers to select a lab for their research. For July 2006 the Adult ID program has recruited an MD/PhD applicant who has been selected as the next candidate for a position on this grant. For July 2007, the Pediatric ID program has recruited another outstanding applicant who has not yet interviewed with the executive committee, but is a strong candidate for inclusion on this grant. Many predoctoral and postdoctoral students are training in the laboratories of the mentors on this grant, which creates an outstanding environment for our trainees. This grant is unique on Penn's campus since it is the only one specifically targeted to train MD or MD/PhD ID fellows. We are committed to providing outstanding training to postdoctoral fellows, including minorities, and we are determined to help develop the next generation of leaders in infectious disease biomedical research.